Optimum load distribution processing is selected and executed based on settings made by a user in consideration of load changes caused by load distribution in a plurality of asymmetric cores, by using: a controller having a plurality of cores, and configured to extract, for each LU, a pattern showing the relationship between a core having an LU ownership and a candidate core as an LU ownership change destination based on LU ownership management information; to measure, for each LU, the usage of a plurality of resources; to predicate, for each LU based on the measurement results, a change in the usage of the plurality of resources and overhead to be generated by transfer processing itself; to select, based on the respective prediction results, a pattern that matches the user's setting information; and to transfer the LU ownership to the core belonging to the selected pattern.